Divinyl sulfone tanned proteins



Patented Dec. 25, 1951 2,579,871 DIVINYL SULFONE TANNED PROTEINS DwightL. Schoene, Naugatuck, Conn., assign!!! to United States Rubber Company,New York, N. Y., a corporation of New Jersey No Drawing. ApplicationJune 9, 1949, Serial No. 98,165

Claims. (Cl. 8-1275) This invention is concerned with new and novel,modified proteins, and a process for producing them.

An object of the invention is to provide new and novel modified proteinproducts. A further object is to react protein substances as they existin various vegetable and animal substances with divinyl sulfone. A stillfurther object is to utilize the reaction of divinyl sulfone withprotein substances in the tanning of animal hides and skins, and inrendering wool alkali-resistant. Further objects will be apparent fromthe hereinafter set forth description.

I have found that proteins will react with vinyl sulfone, (CH2=CH)2SO2,to give products having appreciably altered properties, and which haveutility for a number of applications.

The reaction takes place readily, in some instances without a catalyst,although for most purposes I prefer to add a small quantity of analkaline catalyst. The simplest reaction medium is water but organicsolvents or dispersants may be used if desired. A variety of reactionprocedures may be used depending upon the protein and the end use of theproduct. For example,

wool may be moistened with a dilute aqueous solution of vinyl sulfoneand then dipped into a solution of dilute alkali. The reaction takesplace within a few minutes at room temperature. Alternatively, theprotein may be moistened first with alkali solution and then with thevinyl sulfone solution. In,another method the protein,

e. g.,' casein, is dissolved in alkali and the viscous solution istreated with vinyl sulfone which causes rapid gelation. Non-aqueoustreatments are equally effective. In such cases the protein is treatedfirst with the alkali solution and dried, after which the vinyl sulfoneis added directly or in solution in an organic solvent such as benzene.As before, the reaction takes place rapidly.

The products of the reaction are characterized by their insolubility inprotein solvents. The treatment also confers upon the proteins a goodmeasure of dimensional stability to heat, water, solvents and the like.For example, untreated hide substance shrinks rapidly and partiallydissolves in hot water (50400 C.). After treatment with vinyl sulfonethe product is resistant to boilingwater. In other words, the treatmentprovides a new method for tanning leather.

The concentration of vinyl sulfone required varies with the propertiesdesired in the final product. For example, casein solutions treated withas little as 0.10 percent of vinyl sulfone, based on the weight of thecasein, are altered in viscosity whereas treatments with vinyl sultoneat concentrations ranging from about 1 to 50 percent produce insolublegels. For tanning purposes concentrations of 0.2 to 20% of the sulfone,based on the weight of the skin to be tanned, may be used.

As catalysts, any material which will produce a hydrogen ionconcentration in water or 10-" per liter will suihce. Materials havingalcoholic hydroxyls or amino hydrogen should be avoided since these willreact with the vinyl sulione. Examples of effective catalysts are sodiumand potassium hydroxides, calcium and barium hydroxides, the carbonatesand phosphates of sodium and potassium, the quaternary ammoniumhydroxides such as benzyl trimethylammonium hydroxide and the tertiaryamines such as trimethyl and triethyl amines. The catalysts areeffective but somewhat slow at concentrations as low as 0.1% based onthe protein. For most cases concentrations in the range of 0.5 to 5% arepreferred although concentrations up to 40% may be employedsatisfactorily.

The reaction is equally applicable to animal and vegetable proteinswhichinclude such types as casein, soybean protein, zein, glutenin, gliadin,globulin, hides and skins, oil and vegetable tanned leathers, wool,silk, albumin, gelatin, keratin, collagen, glue, and the like. Thereaction takes place readily at room temperature (ca. 25 C.) althoughtemperatures ranging from 0 to C. may be employed, if desired.

The modified proteins produced by reactions with vinyl sulfone areuseful in a number of applications. Wool is rendered alkali resistantwhich permits the use of alkaline vat dyes. Casein soybean protein andgelatin can be insolubilized to provide paper with improved wet strengthor a permanent size for fabrics. Leather of improved stability and waterresistant glue can also be obtained.

The following examples illustrate the invention:

Example 1 A 10% solution of gelatin in 2% aqueous sodium hydroxide wasmixed rapidly with an equal volume of a 10% aqueous solution of vinylsulfone. Within a few seconds the solution gelled giving an opaqueyellow semi-solid. It dried to a hard, hom-like mass which was no longersoluble in water or alkali.

Example 2 A semi fluid solution of gelatin in water was treated with 5%vinyl sulfone by weight of the gelatin. The addition of an equal volumeof aqueous sodium hydroxide solution caused gelation within a fewminutes.

Example 3 portion was heated to boiling in water and shrank less than Itremained tough and strong. The control shrank markedly in water at about50 C. and almost completely disintegrated on boiling.

Example 5 Example 4 was repeated using a 3% vinyl sulfone solution witha contact time of 3 hours.

The alkali treatment time was increased to 1 hour.

Part of the final product was boiled in water for 15 minuteswithout'causing any appreciable shrinkage. The boiling softened the hidesomewhat making it more flexible than the unboiled portion.

Example 6 Samples cut from the same piece of a commercial, oil-tannedchamois skin were soaked for 45 minutes in aqueous solutions containing0.5%, 2%, and 5%, respectively, of vinyl sulfone. All three solutionsalso contained 0.1% of a commercial wetting agent. The wet pickup was200%. The samples were then placed in a solution containing 2% sodiumhydroxide and 15% sodium sulfate. After 25 minutes they were washed indilute acetic acid and ln-water and were dried. They became slightlystiifer than the control. Their dimensions after treatment were the sameas the control which had been washed with cold water.

The samples, along with the control, were placed in water at 55 C.,heated to 90 C.'and

cooled to room temperature with the followingresults:

1. Control-shrank 30% at 55 C. 2. 0.5% vinyl sulfone-shrank 15% at 55 C.3. 2.0% vinyl sulfoneshrank 10% at 80 C 4. 5.0% vinyl sulfoneshrank 10%at 85 C. Samples (3) and (4) returned to their original treateddimensions on cooling.

This experiment demonstrates that vinyl sulfone is an effectiveretanning agent for leather.

Example 7 A strip of a commercial, vegetable tanned cowhide belt wassoaked for 30 minutes in acetone and air dried. It was cut into twoportions, one of which was placed in an aqueous solution containing 5%vinyl sulfone and 0.1% of a commercial wetting agent. The other wasplaced in a similar solution containing no vinyl sulfone. After 18 hoursthe liquid was poured oil and replaced by an aqueous solution containing2% sodi hydroxide and 15% salt. This extracted some of the tannin andmade the solution and leather dark brown. After 3 hours the samples wereleached for an hour in dilute (1%) acetic acid followed by water. Theacid regenerated the original tan color.

The samples were then boiled for 5 minutes in water. along with aportion of the original belting. This caused both the controls to becomedark brown and curl. The vinyl sulfone treated sample was not visiblychanged. After drying, the controls gave over 20% area-shrinkage whilethe vinyl sulfone treated sample shrunk less than 10%. It also remainedflexible while the two control samples were hard andbrittle.

Example 8 A piece of wool flannel was dipped into a fresh- 1y preparedaqueous solution containing 3% vinyl sulfone and-2% sodium hydroxide,squeezed to about 200% wet pickup, and allowed to stand at roomtemperature. A control sample was similarly treated with 2% sodiumhydroxide solution'containing no vinyl sulfone. After an hour, bothsamples were washed in dilute acetic acid and water and dried. Thetreatment caused 30% shrinkage of the alkali treated sample and only 15%shrinkage of the sulfone-alkali treated material. The alkali treatedsample had a harsh feel while the sulfone-alkali treated sample was onlysl ghtly poorer than the untreated wool. The alkali treated sample andthe untreated control were almost c mpl te disintegrated by a 5% sodiumhydroxide solution at room temperature. Under the same conditions thevinyl sulfone-alkali treated sample was not visibly altered by 5% sodiumhydroxide.

Example 9 A piece of wool flannel was dipped into an a ueous 5% solutionof vin l sulfone containing 0.1% of a commercial wetting agent and wasthen immersed in an aqueous solution cont ining 1% sodium hydroxide and20% sodium sulfate. After 30 minutes the flannel was washed with diluteacetic acid and water and dried. The treatment had no noticeable effecton the hand of the fabric and yet, as in Example 7, it made the woolalkali resistant.

Example 10 To solutions of 10 parts of a commercial soybean protein in50 parts of 5% aqueous sodium hydroxide were added 0.5 part and 0.1part, respectively, of vinyl sulfone. Both solutions gelled within aminute. Similar results were obtained when sodium carbonate replaced thesodium hydroxide.

Example 11 A paste of 10 parts of zein in 20 parts of water was treatedwith 1 part of vinyl sulfone. This treatment caused the zein toagglomerate but, after 30 minutes, a test portion was still soluble inethanol. The balance of the mixture was treated with 5 parts of 25%sodium hydroxide. 30 minutes later, the zein would no longer dissolve in80% ethanol, indicating reaction.

Example 12 10 parts of zein dispersed in 50 parts of a 10% aqueoussodium oleate solution containing excess sodium hydroxide was treated at50 C. with 1 part of vinyl sulfone. Within a minute the reaction productprecipitated and would no longer dissolve in 80% ethanol.

Having thus described my invention, what I claim and desire to protectby Letters Patent is:

1. A method of tanning animal skins which comprises reacting proteinsubstance of the skin in situ with divinyl sulfone.

2. A method of treating wool which comprises reacting the proteinthereof with divinyl sulfone in the presence of an alkaline catalyst.

3. A method of preparing modified proteins having increased dimensionalstability to heat, water and solvents, comprising reacting the proteinwith divinyl sulfone in the presence of an alkaline catalyst.

4. A method of preparing modified proteins having increased dimensionalstability to heat, water and solvents, which proteins are selected fromthe class consisting of soybean, gelatin, zein, casein, wool, and animalskin protein, comprising reacting the protein with divinyl sulfone. inthe presence of an alkaline catalyst.

5. A method which comprises reacting casein with divinyl sulfone in thepresence of an alkaline catalyst.

DWIGHT L. SCHOENE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,290,294 Riess July 21, 1942FOREIGN PATENTS Number Country Date 471,010 Great Britain Aug. 26, 193718,692/34 Australia Feb. 7, 1935 OTHER REFERENCES Chem. Abstracts, vol.41, p. 6306 (1947) citing: Kinsey et al., Jour. of Cellular 8:Comparative Phys., vol. 29 (1947), pp. to 108.

Chem. Abstr., vol. 42, pp. 247-248 (1948) citing: Kinsey et al., Jour.of Cellular & Comparative Phys., vol. 29 1947),pp. 289 to 299.

Jour. of Org. Chem, vol. 11. DD. 719-735, Nov. 1946.

2. A METHOD OF TREATING WOOL WHICH COMPRISES REACTING THE PROTEINTHEREOF WITH DIVINYL SULFONE IN THE PRESENCE OF AN ALKALINE CATALYST.